Integrated heat exchange system

ABSTRACT

The invention provides a method and apparatus for integrating the tube side streams in a plurality of plate fin and tube or finned tube exchangers to accomplish more efficient heat transfer or a more compact design.

TECHNICAL FIELD

This invention pertains to the field of heat exchange and specifically to a more efficient design of heat exchangers.

BACKGROUND OF THE INVENTION

Plate fin and tube heat exchangers or externally finned tube exchangers have long been employed to recover process heat. These exchangers are most often employed to heat or cool a low density gas stream located on the finned side against a denser fluid with higher heat transfer coefficient within the tubes. The extended surface on the finned exterior pass allows greater heat transfer surface than a bare tube and provides greater heat transfer at a low-pressure drop.

Multiple plate fin and tube heat exchangers have been installed in parallel. The tube side headers of each exchanger are typically individually connected to supply and return piping. The art has not heretofore recognized the unexpected advantage of using multiple parallel exchangers while interconnecting the tube side headers of multiple heat exchangers to minimize supply and return piping. This is accomplished by feeding the tube side supply fluid of multiple exchangers through a selected exchanger supply header and returning the tube side fluid of multiple exchangers through a selected return tube side header of a selected exchanger where the tube side headers of multiple exchangers are interconnected to simplify or eliminate manifold piping.

SUMMARY OF THE INVENTION

The invention provides a method of integrating the tube side streams in a plurality of plate fin and tube or finned tube exchangers to accomplish more efficient heat transfer, to simplify piping, or to provide a more compact design. The tube side supply and return headers of a plurality of coils are interconnected together. A selected coil can then be supplied the tube side fluid which is feed to the other coils through the interconnected supply headers. The return fluid interconnected headers can then return the fluid to external piping thought the tube side return header of a selected coil.

The invention may be employed to simplify the heat exchange of any gas turbine inlet air heating or cooling or exhaust heat recovery system or other device that produces a waste heat exhaust or is a source of process heat. Alternatively the arrangement may produce more efficient refrigeration at locations requiring refrigeration or cooling.

In summary, the invention provides a system for heat transfer in a plate fin and tube or finned tube exchanger by providing a simplified integrated tube side circuitry.

The invention is illustrated by the specific example set out below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sketch of a typical coil system having two working fluids in separate circuits. A first working stream such as a gas is directed across the fin side of the coil. Piping manifolds supply a second working stream to supply connections on the multiple coils to feed the tube side headers. A piping return manifold takes the working fluid from the multiple coils return tube side headers. The first working stream is heated or cooled while cooling or heating the second working stream.

FIG. 2 is a sketch of an integrated coil with integrated flow paths. A first working stream such as a gas is directed across the fin side of the coil. A second working stream is supplied to one coil supply manifold where the second working stream is distributed to the tubes in that coil and to the header of another coil where the second working stream is distributed to the tubes in that coil. Multiple coils can be supplied with the second working stream in this manner. The second working stream coil return manifolds can be attached in a similar manner such that the second working fluid is discharged from multiple coils via the return header connection of one coil.

DETAILED DESCRIPTION OF THE INVENTION

The invention may be described in several ways as alternate embodiments of the same novel discovery.

A method for operating a heat exchanger of the plate fin and tube or finned tube type that can be used in heat transfer system that comprises:

-   -   a. providing a first working fluid on the finned exterior side         of two or more heat transfer devices,     -   b. providing a second working fluid flowing within the tube         circuits of the plurality of heat transfer devices,     -   c. feeding the first working fluid to the exterior finned side         of a heat transfer zone or zones to transfer heat to or from the         first working fluid thereby heating or cooling the first working         fluid to a higher or lower temperature,     -   d. feeding the second working fluid into a header of one heat         transfer device feeding a group of tubes to be heated or cooled         by the first working fluid in the first heat transfer device as         well as feeding fluid and receiving return fluid from other heat         transfer device(s).

In a preferred embodiment the invention provides:

-   -   e. a plurality of heat exchange devices having a finned exterior         side working fluid streams against multiple tube side circuits,     -   f. the multiple tube circuits being interconnected to more         effectively feed a plurality of heat transfer devices.     -   g. Feeding one heat exchange device with the second working         fluid while also feeding the second working fluid from the first         heat exchange device to other heat transfer devices.

In a more preferred embodiment the invention further provides:

-   -   h. A method of circuitry of a plate fin and tube or finned tube         exchanger that allows for more effective heat transfer by         providing a working fluid in separate integrated circulation         paths.     -   i. A method of construction and design allowing complex         circuitry of a plate finned and tube or finned tube exchanger         utilizing multiple tube side circuits that are integrated to         accomplish a simplified supply and return circuit than would be         possible with multiple tube side fluid streams arranged in         series without integrating the circuitry.

The inventive concept may also be embodied as a method for an energy recovery system for increasing the efficiency of a gas turbine inlet air or exhaust heat exchange by providing an integrated tube side cooling or heating circuitry to cool or heat a working fluid circuit(s) while cooling or heating the inlet or exhaust stream of the gas turbine. 

1. A method for operating a heat exchanger of the plate fin and tube or finned tube type that can be used in heat transfer system that comprises: a. providing a first working fluid on the finned exterior side of two or more heat transfer devices, b. providing a second working fluid flowing in separate circuits within the tube circuits of the plurality of heat transfer devices, c. feeding the first working fluid to the exterior finned side of a heat transfer zone or zones to transfer heat to or from the first working fluid thereby heating or cooling the first working fluid to a higher or lower temperature, d. feeding the second working fluid into a header of one coil feeding a group of tubes to be heated or cooled by the first working fluid in the first heat transfer device as well as feeding fluid to other heat transfer device(s).
 2. A method for operating a heat exchanger of the plate fin and tube or finned tube type that can be used in heat transfer system that is comprised of a plurality of heat exchange devices having a finned exterior side working fluid streams against multiple tube side circuits, the multiple tube circuits being interconnected to more effectively feed a plurality of heat transfer devices.
 3. A method of circuitry of a plate fin and tube or finned tube exchanger that allows for more effective heat transfer by providing a working fluid in separate integrated circulation paths where the exchanger supply or return manifolds are interconnected between a multiple of heat exchangers with the fluid being supplied to multiple coils thru the connection of one coil.
 4. A method of construction and design allowing complex circuitry of a plate finned and tube or finned tube exchanger utilizing multiple tube side circuits that are integrated to accomplish a simplified supply and return circuit than would be possible with multiple tube side fluid streams arranged in series without integrating the circuitry.
 5. The method of claim 1 wherein the first working fluid and the second working fluid have the same composition.
 6. The method of claim 1 where the second working fluid contains water, a glycol brine, an alcohol brine, a formate solution, or contains more than 5% by weight of a component listed by ASHRAE.
 7. A method for designing an energy recovery system by integrating the tube side streams in a plurality of plate fin and tube or finned tube exchangers to accomplish more efficient heat transfer or a more compact design.
 8. The method of designing a heat transfer system to simplify the heat exchange of any gas turbine inlet air heating or cooling application or exhaust heat recovery system or other device that produces a waste heat exhaust or is a source of process heat by integrating the tube side streams in a plurality of plate fin and tube or finned tube exchangers. Alternatively the arrangement may produce more efficient refrigeration at locations requiring refrigeration or cooling. 